module Extender (
    input [15:0] immediate,
    input Sign,
    output reg [31:0] extend
);
   
    always @(*) begin
         if(Sign)//符号拓展
            extend={{16{immediate[15]}},{immediate[15:0]}};
        else
            extend={{16'b0000000000000000},{immediate[15:0]}};
    end
   

endmodule //ext